This invention concerns an assembly comprising a housing having a bore, or a shaft, an article which is positioned in the bore or mounted on the shaft, and a device which is also positioned in the bore or mounted on the shaft and prevents movement of the article along the bore or the shaft in the direction from the article to the device.
Known ways of preventing an article, such as a rolling bearing, gear or the like, mounted on a shaft from moving in one direction include an abutment, for example a shoulder provided by the shaft. Movement in the other direction would be prevented by a circlip, or a collar through which extends retaining screws, or a nut co-operating with a screw-thread on the shaft, or a clamp plate retained by bolts screwed into the end of the shaft.
Patent Specification GB No. 1392182 (Airscrew) (published 30 April 1975) discloses an assembly which comprises a hub and a collar each with a bore through which a shaft extends. The collar is connected to the hub either integrally or by means of a screw and is held in a tilted position by another screw to produce a clamping effect. However this assembly is relatively complicated, so making production relatively expensive, and is bulky. Also difficulties can be experienced in mounting the hub and collar because of the screws.
Known ways of preventing movement of an article positioned in a bore of a housing include a circlip, or an externally screw-threaded nut, or an end cover or cap which is clamped to the housing with a suitably machined spigot or a shim placed between the cover or cap and the article.
These known ways suffer from various drawbacks: the groove for a circlip needs to be machined and carefully positioned. Even so with the build up of tolerance a clearance may still arise between the circlip in the groove and the article resulting in an unacceptable movement. The use of a nut requires a screw-thread to be cut on a shaft or in the bore of a housing--which is a relatively expensive operation--and the provision of a means to prevent the nut from moving during use. Further, there can be difficulties in using tools to adjust the nut and to fasten the means to prevent the nut from moving. Collars which are retained by screws for example, can be difficult to place accurately and having a limited capability to prevent axial movement of an article. The use of a cover or cap requires screw-threaded bores to be produced in the housing or shaft by drilling or tapping. It also requires fitting by a skilled or highly experienced person to establish and fit suitable packing shims between the cover or cap and the article, or the machining of a suitable spigot which is integral with the cover or cap.